Method of and apparatus for measuring the stringing of shot.



S. W. FARNHAM & F. W. OLIN. METHOD 0F AND APPARATUS FOR MEASURING THE STRINGING 0F SHOT.

APPLicAnoN FILED 11116.10. 1914.

1,226,762. Patented May 22, 1917.

A. 2 SHEETS-SHEET 1. l ,30 /6 gif/265565:

S. W. FARNHAM I F. W. OLIN.

METHOD 0F AND APPARATUS FOR MEASURING THE STRINGING 0F SHOT. APPLICATION FILED AuG.1o. I9I4.

1,226,762. f Patented May 22, 1917.

2 SHEETS-SHEET 2.

i i I' APAT l SIDNEY w. rum-IAM, or cmcAGo, Ann rnANiinm w.- oLnt, or nLToN', mmosgf l Assrenons To WESTERN cAnTnmen COMPANY, or. EAST Amon, nmmors; A con'- ronATIoN or NEW msm.

- METHOD or AND APPARATUS non MnAsUmNe Tnfn sTnmGnG or snor.-

wastes.

To all whom t may concern.'

Be 'it known that we, SIDN W. FAEN- HAM, a citizen of'the United lSxtatesvand aV resident of the city of Chicago, in the county.

of Cook and State'of Illinois, andlllRAru4 LIN W. OLIN, a citizen of the United States,

ment in Methods of andiApparatus for Mees-- uring the Stringing of Shot, of which the following is a specification.

This lnvention relates to theproving or testing offshot guns or fowling pieces and fixed ammunition or shells such`asare used for sporting purposes, and consists in meth ods of and means for determining the'I dis= tribntion Vor grouping of the shot in `a'load -at a 4predetermined distance from the muze zle of the gun. It is well known that a load of shot discharged from an ordinary fowling piece .scatters after leaving the muzzle, and it is the aim of gunmakers and shell makers to regulate the scattering of the shot and to cause it to be uniformly distributed with `respect to planes transverse to its trajectory at successive points along its line of flight. The scattering transverse to' the line of Hight may be observed by placing a paper targetvacross the trajectory at the desired point andnoting the position of the holes .l perforated bythe respective. shot;but the scattering of the shot behind one another along the line of flight, or Stringing can-` not be observed bythis method. The object of this invention is the' determination off both rth'eJ transverse distribution, or scatter` ing, and longitudinal distribution, or string-v ing, of the shot in a load at a predetermined distance from' the muzzle of the gun; 1

The form of apparatus devised by us for accomplishing this objectv consists Aessentially of olie stationary and one or more moving targets, at "andthrough which the load of shot is iired. lnorder that the velocity of the shot maynot be affectedby itspassage' throughithe targets, and toavoid delecting the shot from their straight line paths/ the targets -should be of uniform material easily pierced by the shot, such as paper, The firstv target is stationary'and is clamped around vits' circumference on a suitable frame. VThe l second target is f @ousted forv reevenem Y Specification of Vletters Patent. j Pajmngd 917. i Application mea'Aug-ust 1o, isnt. seriaxn. 856,103. i Y

supporting device vwhichV willy maintain the across the -pathvofitheshot at a short-dis'- i tancev behind the first one,.by means of al second target in a plane parallel tothe first v at whatever velocity` it may be moving; Be- 1 hind the second target there may be-located Y a' third paper. target, arranged,` for movement ina, direction eitherA the same as or di'e'rent from' 'the second one, 0and at the j lication of the respective pellets in the load,

as hereinafter explained. The moving tarlgets may be strips or bands of papermoving ..1 n straight orcurved lines transverse to the'A path of the shot, orthey maybe'paper disks rotating 'about their 'centers directly ,inV vthe path of the shot.

lf rotating targets-be used, as inthe ape. -paratus described herein, the angular velocity thereof shouldbesuiciently lowrso that the Vangle traversedlbetween thetimes of I penetratipn ofth'irst and lastpellets in Y' any charge-of shot will not. exceed .0n-ehm; Y

dredr andv eighty degrees. Thefidentiication "801.

of the respectivepellets in a VVloa'dfor charge clan' be. made more conveniently the speed fyf is reduced to such a vspeedthat 'the'greatest angle traversed-by the targets between the". l

timesXof penetration of the first and last pel-'A lets will not exceed 15 or 20 degrees;v Kno'vw :ing the angularvelocity of the rotatingtar. i

Vget 'or targets,'by observing theangles trav- Versediby such targetfor targets" between the timesof penetration oftherespective 'pelletsv their distances apart,"measured -in fractionalparts ofV a second, along the line o fight calculation, as hereinafter described.' 1 Y v maybe determined by a" simple arithmetical 1 pellets along the' line of .Hight Vthe gpegdf f E 2 termined, and this may be'done by observe ing the angley traversed by the second rotaia.;v

ing targetl during the passage of each pellet rotating targets, as hereinafter described.

of shot at any kgiven'distancefomIthe'gun.' may' 10e-readily gpprorseated by the 11S@ et each pellet in feetrper-second must' bede- 'However, as the laverage velocity of the load.'

well known formulas based upon the muzzle velocity, which in turnvmay be determined for each charge by means fof the chronograph, we may dispense with the third rotating target and calculate the ldistances apart of the respective pellets, in feet'along the line of flight by multiplying their dis-v In the drawings, in which like characters designate like parts wherever they occur,

Figure 1 is a side elevation of the apparatus, partly broken away to show the upper portion in section on a vertical central plane; j

Fig. 2 is a half front elevation, and half section on the line 2 2 in Fig. 1; the targets and cardboard backing being partly broken away to disclose the parts beneath;

Figs. 3, 4 and 5 are front views of the three paperv targets after a loadof shot has passed through; y

Fig. 6 is a view of the target shown in' Fig. 3 upon which the points at which the respective shot passed through the targets shown in Figs; 4 and 5 have been traced, the

two last mentioned targets being superposed on the first in their respective instantaneous angular positions at the times a selected shot passed through them; and v j Fig. 7 is a part cross-section through the supporting members nfor the targets on the line 7-7 in Fig. 2, showing the points in side view.

Referring to the drawings, the apparatus comprises I a stationary annular frame 11 mounted between the front ends of the side index needle frames 12--fto which it is bolted. A circularpaper target 3 is clamped to this stationary frame around its circumference by a ring 13 secured by bolts 14 and wing nuts 15 or other suitable clamping means. To the rear of the stationary target 3 are mounted one behind the other two circular paper targets,

4, 5, clamped around their circumferences to .an annular frame 16 and disk 17 respectively, by means of rings, 18, 19,secured by thumb screws 20 or other suitable means. The frame and disk are concentric, and are mounted for rotation. about' the same axis.

The frame 16 is ixed on the front end of a vhollow shaft 21 journaled in bearings 22', 23 in pedestals`24, 25 on a plate bolted to 'ing the pedestals the side frames behind the targets. The shaft 21 has keyed to it a drivingfpulley 26 to be belted to an electric motor or other source of power. The disk 17 is supported on the front endof a hollow shaft 27? mounted for rotationv withinl and projecting beyond the ends of the shaft 21, and driven by an annular gear 28 fixed upon its rear projecting end. The` annular gearr 28 `is driven from the pulley 26 by means of a spur gear 29 lixed on the hub of the pulley and a short shaft 30 mounted in a block 37 in the pedestal 25 and carrying on its ends spur gears'31, 32 meshing with the spur gear 29 and annular gear 28 respectively. The

sizes andJ arrangements of these gears is such that the shaft 27 is rotated at the same speed asv and in the direction opposite to the shaft 21, thus causing the targets 3, 4, carried by the shafts to be rotated at the same,

speed and in opposite directions. Itis evident that the sizes and arrangement of the gears may be such that the targets are rotated at different speeds in the same or in opposite directions if desired. Between the target 5 and disk 17 is a layer of cardboard 33 or other soft material in which the shot embed themselves and are retained after passing through the targets. Axially mounted within the hollow shaft 27 is a centering needle 34 for pricking the centers of the rotating paper targets and for locating the center of the stationary target concentric with respect to the rotating: targets. A slide 35, moved and locked in. place by a thumb screw 36, covers the open end of the shaft 27 Vat all times except when the centering needle is being used.

At a convenient point on the edge of the frame 11L against which the target 3 is clamped is fixed an index needle point'42 projecting through the target into a hole 43 in the clamping ring 13. Similar index needle points 38, 40 are fixed in the edges of the rotating frame 16 and disk 17 to project. through the targets 4, 5 into holes in the clamping rings 18, 19. The index needle points are so located with respect to each other than whenl the index 38 in the rotating frame is in the same diametral plane with the index 42 in the stationary frame the index 40 is also in the same diametral plane therewith. j l

The space betweenthe annular frame 11 and the rotating frame 16 may be varied by sliding either the frame 1l or plate carry- 24, 25 along the side frames, and this space should be adjusted so that the Wind of the shot and the air suction due tothe centrifugal effect of the rotating targets will have a minimum effect on the rotating target 4. Dishing of the target 3 and variations in the distance between the targets 3 and 4 have no effect on the average angular distance rotated through by the rothe targets 4 and 5 ymust be kept'flat in their planes of rotation with Vthe distance between them constant; in order to attain a same letters in Figs.'3, 4 and 5 are those made by the same pellets, respectively. In anypattern it is possible to find a pellet hole yhaving a radial distance from the cen- 25 ing thrown olf the machine leaving the rol get- -65 being caused by the sane pellet on each of selected as the reference pelle ter of the Y,target different from that of any it is .the object of our` invention-toaccomv other pellet holes.

plish. a f

rlhe target 3 (see Fig. 3) visina'rked. with with the similarity of the pattern on all concentric circles and with radial at I three targets, especially noticeable near theV g uniform angular distances apart for'^con center where the amount of distortion of venience in operating the apparatus,'as will" the patterns on the moving targets as combe fully explained hereinafter.- The targets pared with the stationary one is slight, will- 4 and '5 may be' marked with circles and make this identification certain. Whenthe radial lines Similarlyto the target 3, (5i-,they markof some one individual pellet has been '15 may be left plain. r1`he target-4is not essen- -absolutely .identified on both the`rotating l tial, "and may be omitted in the operation of and the stationary targets, then one of the v p the apparatus, but we-preferto use it in vrotating targets is placed over the stationary i .order to' obtain a check uponv the accuraey one with their centers coincident, and with of the observations made with the targets tllGfPOIltS f Penetration Of this particular 2g 3 and 5. pellet coincident on bothtargets. By means In the operation of the apparatus the of a suitable marker the points of penetraplain. paper targets 5 vand 4 are stretched tion of the other pellets on the rotating tarupon the disk17 and'frame 16 respectively, `get and the llle made by the llndefv p OlIlt and Securely clamped, the driving power beare marked' through on the stationary tar- Similarly the second rotating 'target tating p arts free. to revolve as may be re- IIQX iS Plad UPOII the ,Stallonl'y target quired ,during this operation. The holes Wlth the'hQlQSmad by the $31116 reference Where the'index points 38, 40, Piera@ the pellet coinciding, and the points where the v-tatingtargets., as hereinafter explained, `the lthree targets. The holes bearing the This feature, togetherV vtargets should be vplainly designated, The pellets penetrated the rotating target and target 3, marked with radial lines and contll llOle Iliade by JlleIlleX PQIl aire SPQtlledcentric circles, is next, stretched upon the 0n the Stallfllalf target Wllll marks C01-l Y stationary frame 11, ca re being takenl to o Ol'ed S0 21S t0 dlstlllgulsh the PtteI'll'tlluS adjust it so that itscenter is in line with made fOm that mad? 'from the first rotatlng the axis of the centering needle 34, which target.

may be'thrust through `the targets 4 and ,5 0n removing the rotating target and obin order to-bring its point into the prox- Serv/111g the patterns traced on the stationary limity with the target 3, and care also being 011e it Will be OUIld' that OI every hole taken that the index point 42 passes through a radial line-[If targets4 and 5 are marked` target there will be two marks adJacent 4o like tai-get 3 care Vmustgloe taken that their thereto on a circle concentric therewith, cors centers coincide with the axis of the centerresponding to the .holes made -b the 'same ing needle. In either case, the centers of Pellet in th fotatmg target?? t SSB marks :o targets 4 and 5A lmust be pricked 'by\ the cenor traces will be-about equi-,distant from the tering needle before they are ancla/mpeg'. pellet hole and should be ex ctly. so 1f the 45 After theL centering needle is'withdrawn the three paper targets could e entirely preplate 35 is slid over the opening` in the center of, the' disk 17 .pand clamped by the traveled 1n parallel paths. rlfhe third target thumb-screw 36 The driving powers then 'is useful'in positlvely identifying the-holes thrown on and the" targets 4 and 5 set in mad@ by the respective PelletS,even YVllIl it 5e' rotation. We find 200 revolutions'per min-H isznot used in determining the velocities of ute a convenient. speed at which tov rotatel theppellets, .by reason of the fact that when the targets. -This speedcorresponds to un several pellets passed through the targets angular-'velocity of 1200 degrees per second; close together and at abOllt the Same radial that is, one degree o'f rotation requires a distances from the center it would be impostiineinterval of n10-6 seconds. sible to identify their traces from one rotat- Next, a charge or load of shot is fired at ing, targetl alone; but by pairingeachv trace the targetson a direct line with their een I'OIII 011e ,I0ttI1gtarget with a tI'aCeI'Om ters. The' shot penetrate the stationary and 'thevother/ rotating target at the same dismoving targets almost simultaneously, but. tance on the opposite side of a pellet hole, ity ssome pellets of shot'will strike earlier and may'jbe determined with certainty which some later than the average'shot. The tartraces and," holes correspond' to the several made by a pellet penetrating the stationary l vented jfrom vibrating, arid if the pelletsall gets are then removed from the frames, and pellets.. Fig. 6 shows. the target 3 after the by the assistance of the concentric circles holes lma/de by the shot in targets 4 and 5 certain isolatedholes can be identified as have been traced thereon, the pelletF-being In Figs. 3 and 6 the holes made in the targets by the same pellets are indicated by the letters A, B, C, D, E, F, G, H, .land K, respectively. In Figs. 4 and 5 the holes, and in'Fig. 6 the traces of the holes in targets 4 and 5, are indicated by the same letters with prime and'double prime marks added to, indicate which target they were made in or Atraced from,vthe primed letters' indicating holes or traces of holes made by the respective shot or pellets in target 4 and the double primed letters indicating holes or traces of holes made by the same pellets in A.

target 5. Some of the pellets penetrated the targets earlier and some later than the reference pellet F above referred to, and the approximate order or sequence of the pellets AThose pellets that penetrated the targets at the same instant the reference pellet did will have theirmarks ,or traces coincident with i the pointsl where they penetrated the stationary target.l Thus, referring to Fig. 6, it is evident that Athe pellet H penetrated the targets at the same instant A'with the pellet F,

and that the vpellets B, C,D,E and G penetrated earlier'and the pellets A, J and' K.

penetrated later. rIhe pellet K' 'passed through theusarne hole in the station-ary target as the pellet B, but at a later instant.

The angular distance between the hole made by a pellet in the stationary target vand its trace thereon measures the number of degrees through which the corresponding rotating target revolved between the instant of penetration thereof of that -pellet andthe instant of penetration yof the reference pellet, and therefore, said angular distance is proportional to the time interval. between theinstants of penetration of said pellet and thereference pellet. vThere will be a slight variation in the angles between thefrespective holes and their traces from the two rotating targets, due to the vibration of the paper targets, but error from this cause is largely compensated for by taking the aver-y age of the angular' distances of the two traces from e'ach pellet hole. By measuring the angles between the lines drawn to the center from the two traces on the stationary target indicating the'holes made by a pellet in the-moving targets, and then dividing by two, the average angular distance or displacement in degrees for that pellet isY found. The average angular displacement of a pelletin degrees divided by the angular velocity lof the rotating targets in degrees per second equals the timeA interval in seconds between the instant of penetrationl of ,said pellet and the instant of penetration of the reference pellet.

The distances in feet measured along the line of flight between the respective pellets and the reference pellet are equal to thevelocities of the respective pellets in feet per second multiplied by the time intervals in seconds between their respective instants of penetration and the instant of penetration of the reference pellet. I

The velocities of the respective pellets in feet per second may be computed separately for each pellet by observingthe angle traversed by the target 5 while the pellet was crossing the space between the targets v4 and 5. Assuming that, in' the apparatus herein described, the space between the targets 4 and 5 is 5 inches, and the target 3 is 5 feet 3 inches in diameter, then an angle of one degree will measure upon the lcircumference of the target inches. yMeasuring the length ofthe arcs of the circumference between the referencepoints X and Y and X and Z we find that the reference pointZ is inch farther removed: from the reference point X than is the reference point Y, corresponding to an angle of divided by target 5 while the pellet F was crossing the space between the targets 4 and 5. At 200 revolutionsper minute the time interval required for the target 5 to rotate TT degrees is found by dividing the number of degrees -by 1200 (each degree of rotation requires a must have hfad a velocity of f5, feet divided. vby ,34m seconds, or 1100 feet per second. This velocity may be assumed to be the average velocity of the pellets.

The distance in feet measured along the line or Hight between any pellet andthe reference pellet can be approximately calculated, knowing the average velocity of the shot, by multiplying its angular displacement in degrees by its average velocity. in feet per second and dividing by twelve hunvvdred, where the targets were rotated at two hundred revolutions per minute. When the rotating targets have other speeds than two hundred revolutions per minute (correspending to an angular velocity of 1200 degrees per second), the number to be used as a divisorfshould correspond thereto. Tak-A ing the pellet A, for example, the average angular displacement (see Fig. 6u) is fifteen degrees. If the targets were lrotated at two hundred `revolutions per minute, and the 4, or ,if degrees, rotated through by the To have crossed the space between average linear velocity of the .Shot was 8. In apparatus of the character de-` scribed, a lstationary target and a moving target arranged in alinement, one of said targets being made of a material easily pierced by shot, means for maintaining the movement of said moving target during the passage of a load of shot, and means for ascertaining the velocity of thel movingI August, 1914.

`means yfor maintaining the synchronous y movement of said targets during the passage of a load of shot.

Signed at Chicago, Ills., this 27th day of 20 Ju1y,.1914.

SIDNEY W. FARNHAM. h Witnesses to the signature of S. W. Farn- FRED H. JOHNSTON,

.FRANCIS- L. LARUE. Signed at St. Louis, Mo., this 5th day'of FRANKLIN W. OLIN.

Witnesses to the signature of F. W. Olin:

J. M. OLIN, l M. A. SHELfroN. 

